A prominent Palestinian political leader accused Israel of attempting to assassinate him yesterday, hours after a mysterious explosion rocked his home in the West Bank city of Ramallah.

Qais Abdel Karim, known as Abu Laylah, made the accusation four days after two Israeli guided missiles burst through the windows of a Ramallah apartment block, killing the leader of the Popular Front for the Liberation of Palestine, Abu Ali Mustafa, as he sat at his desk.

It underlines the fragility of the efforts to arrange ceasefire talks between the Israeli foreign minister, Shimon Peres, and the Palestinian leader, Yasser Arafat.

Mr Peres's aides say they could meet next week, but all bets are off if Israel and the Palestinians again succumb to the violence that followed Mustafa's assassination on Monday.

The killing - which Israel admitted - set off a tumultuous week in which Israeli tanks and troops entered the Christian town of Beit Jala after the nearby Jewish settlement of Gilo came under fierce fire from Palestinian gunmen.

The 51-hour occupation took 11 months of violence past all previous milestones of escalation, and ended only after EU officials intervened.

Abu Laylah said he left his home at midnight on Thursday after he became worried about persistent helicopter activity above the building. Fifteen minutes later a bomb exploded in a computer warehouse on the ground floor, scorching the upper stories, and hurling steel doors into the road.

As leader of the Democratic Front for the Liberation of Palestine he, like Mustafa, was one of the five most prominent Palestinian figures. Unlike other Palestinian groups, however, the DFLP opposes attacks on Jewish civilians in Israel.

A week ago DFLP commandos stormed an Israeli base in the Gaza Strip, killing three soldiers, and Abu Laylah had been expecting retaliation.

"The Israelis have a list and they are trying to score as many successful hits as possible to boost the moral of the army, especially after their failure in Beit Jala," he told the Guardian yesterday.

"This may be why they acted so hastily, and the attempt failed."

An army spokeswoman said Israel knew nothing about the blast. Other officials dismissed the explosion as a "work accident", the usual terminology here when a Palestinian bomb-maker accidentally blows himself up.

But, unlike most "work accidents", it injured no one, and the episode joins a growing catalogue of mysterious explosions in the West Bank and Gaza since Israel began assassinating Palestinian activists in November.

Human rights groups say it has assassinated more than 40 activists and nearly 20 innocent bystanders. Israel has claimed 11 assassinations, all carried out from helicopters in daylight, but it is official policy not to admit all the killings.

At least 11 other Palestinian activists had died in mysterious circumstances, Salah Abdul Jawad, head of the political science department at Bir Zeit University in Ramallah, said.

He said the ambiguity was intended "to create confusion, and fear".

"In general, Israel admits assassinations only if they are in daylight and there is a clear risk of being filmed by journalists."

The psychological part of the strategy has been very effective. In Ramallah many people believe that every Palestinian leader is now a potential target, and that Israel no longer distinguishes between political and military activists.

Israel says that the strategy of assassinations is part of the war of nerves.

"If they are on the run and have to worry where they are going to sleep at night, that gives them less time to plan the next suicide bombing," a spokesman for the prime minister, Ariel Sharon, said.

 Javier Solana, the EU's foreign policy chief, will press the Israelis and Palestinians to call and honour a ceasefire and resume peace talks when he visits the region tomorrow, officials in Brussels said last night.

He will meet Mr Sharon and Mr Peres and have separate talks with Mr Arafat. He will also visit Jordan and Egypt.